The present disclosure relates to improved methods and apparatus for damaging hair follicles (for example, useful for hair removal) using laser light and/or pulsed incoherent light.
Selective photothermolysis is a surgical method, introduced by Anderson and Parrish in 1983 (“Selective Photothermolysis: Precise Microsurgery by Selective Absorption of Pulsed Radiation”, Science, Vol. 220, pp. 524-527), for destroying certain diseased or unsightly tissue, on or near the skin, with minimal damage to the surrounding healthy tissue. The tissue to be destroyed must be characterized by significantly greater optical absorption at some wavelength of electromagnetic radiation than the surrounding tissue. The method consists of irradiating the target and the surrounding tissue with pulsed electromagnetic radiation that is preferentially absorbed by the target. Because the target absorbs the incident radiation much more strongly than the surrounding tissue, the surrounding tissue is usually heated negligibly.
In the past decade, many laser and flash based devices for removing unwanted hair based on the principle of selective photothermolysis have been introduced into the market and to date, this technique is in wide-spread clinical use. During treatment, the skin of the treatment region is irradiated by a beam of light, and the melanin-containing hair follicle absorbs the delivered electromagnetic radiation, resulting in a temperature rise and destruction for the follicle.
Unfortunately, according to this treatment procedure, the light delivered to the treatment region concomitantly heats the nerve-containing melanin-rich epidermis of the patient, and thus, in many clinical situations, light-based hair removal is considered a painful procedure.
There is a widely recognized need for, and it would be highly advantageous to have an improved method and apparatus for hair treatment which heats hair follicles to a sufficient temperature to damage the hair follicles and to facilitate hair removal while delivering a minimal amount of thermal energy to the nerve-containing epidermis. This could be useful for meeting a long felt market need for comfortable hair removal.
The following published patent documents provide potentially relevant background art, and are each incorporated herein by reference in their entirety: US Application 2005/0215988; U.S. Pat. No. 6,485,484; WO 2005/079687; U.S. Pat. No. 6,544,259; U.S. Pat. No. 5,632,741; U.S. Pat. No. 5,752,948; U.S. Pat. No. 6,214,034; U.S. Pat. No. 6,273,884; U.S. Pat. No. 5,683,380; U.S. Pat. No. 6,514,243; US Application 2005/0143792; U.S. Pat. No. 5,735,844; U.S. Pat. No. 5,595,568; US Application 200210019624; US Application 2005/0143792.